HDFC Bank — Fastag not received

I have applied for fastag from HDFC Bank in last week of October 2020. I had paid the whole amount (Rs 500) of fastag and it has been issued to me. But, I have not received my fastag from 2.5 months. I have contacted them on toll free no. for 9-10 time and always I have been asked to wait for 7 days. I am a valuable customer to HDFC Bank and I was not expecting such a bad service from HDFC Bank. Please look into the issue or refund my money as soon as possible. I would rate HDFC Bank very poor for their fastag services.